The overall objective of the proposed research is to contribute toward the understanding of the molecular mechanism of action of hemoglobin. A specific objective of this research is to establish the complete primary structures of the major and minor cat hemoglobins and to relate them to known differences in their functional properties. Structural relationships will be examined to determine whether the minor components are direct gene products or post-translational modifications of the major components. Studies on hemoglobin biosynthesis will also be conducted to ascertain whether some of the minor hemoglobins are direct translational products of mixed cat globin mRNA, and whether they could be products that result from gene switching. Cat and rat hemoglobins are peculiar among animal hemoglobins in that they selectively bind toxic trialkylmetals; they thereby serve as models to understand the nature of the interaction of the compound with other reactive proteins. An objective of this work is to elucidate the bonding sites on cat hemoglobin, factors that affect the binding, and the functional consequences of the interaction. Another objective of this work is to develop a better understanding of the relationship between methemoglobin conformation and reactivity of the hemes. The effects of quarternary structure on the kinetic activity of the alpha and beta hemes will be analyzed by measuring rates of oxidation and reduction as well as the peroxidase activities within valency hybrids and other forms of of hemoglobins under conditions that perturb the conformation of the protein. The mechanism of activation and inhibition, including non-equivalence in alpha and beta heme reactivity, is of interest.